The invention relates to a drive system on the basis of a double-fed asynchronous motor.
In the so-called power converter cascade of a double-fed asynchronous motor, rotor currents or rotor powers occurring are generally dissipated via slip rings. However, the slip rings are susceptible to interference and maintenance.
The invention is based on the object of providing a drive system based on a double-fed asynchronous motor which does not require any slip rings and which has improved operational properties in comparison with conventional double-fed asynchronous motors.
The invention achieves this object by a drive system according to an embodiment of the invention.
The drive system has a three-phase motor and at least one inverter.
The three-phase motor conventionally has a shaft driven by said three-phase motor.
The three-phase motor furthermore has a first three-phase stator winding, which is conventionally to be connected or is connected directly to a three-phase AC voltage grid, in particular without an inverter interposed, in order to generate a first magnetic stator rotating field.
The three-phase motor furthermore has a second three-phase stator winding, which is to be connected to the three-phase AC voltage grid in such a way that a second magnetic stator rotating field rotating in opposition is produced with respect to the first magnetic stator rotating field, which is generated by means of the first stator winding.
The three-phase motor furthermore has a rotor winding system, which is mechanically coupled in rotationally fixed fashion to the shaft. The rotor winding system can have coil groups distributed uniformly over the rotor circumference.
The at least one inverter is mechanically coupled in rotationally fixed fashion to the shaft, i.e. rotates with the shaft, and is electrically coupled to the rotor winding system, wherein the at least one inverter is designed to generate actuation signals in the form of actuation voltages and/or actuation currents for the rotor winding system in such a way that a first rotor rotating field and a second rotor rotating field, which is different than the first rotor rotating field, are generated, wherein the first rotor rotating field interacts with the first stator rotating field in such a way that a first motor speed and a first torque are produced, and wherein the second rotor rotating field interacts with the second stator rotating field in such a way that the first motor speed and a second torque are produced, wherein the second torque has an identical direction of action or direction of rotation with respect to the first torque.
The two stator rotating fields rotate in opposition. This results in rectified torques between the synchronous speeds.
The at least one inverter can be designed to generate actuation signals for the rotor winding system in such a way that a rotor power transmitted via the first stator winding is compensated for by a rotor power transmitted via the second stator winding.
A common stator magnetic circuit or stator core circuit can be assigned to the first stator winding and the second stator winding, wherein the stator magnetic circuit can conventionally comprise laminate stacks, etc., for example. The first and second stator windings therefore form a stator winding system.
The first stator winding can have a first pole pair number p1, and the second stator winding can have a second pole pair number p2, where p1≠p2.
The rotor winding system can have 2* (p1+p2) coil groups distributed uniformly over a circumference of the rotor winding system.
The drive system can have precisely one inverter having at most 2*(p1+p2) phases or phase connections.
Precisely one single rotor magnetic circuit can be assigned to the rotor winding system. Alternatively, the rotor winding system can have a first rotor winding having an assigned first magnetic circuit and a second rotor winding, which is separate from the first rotor winding and has a second assigned magnetic circuit, which is separate from the first magnetic circuit.
The drive system can have a fan impeller driven by means of the shaft, wherein the at least one inverter is coupled in rotationally fixed fashion and is coupled thermally to the fan impeller. The inverter(s) can be fastened at or on the fan impeller, for example in any desired position, for example in the region of the center of rotation of the fan impeller or outside the center of rotation.
The inverter(s) can be integrated in the fan impeller, for example by virtue of the fan impeller forming a housing for the inverter(s).